gigasecond_birthdate.js

// exercism.io exercise
// This function takes a date and returns a new date set one billion seconds (or gigasecond; ~31.558 years) in the future.
var Gigasecond = function(birthdate) {
  this.birthdate = birthdate;
};

Gigasecond.prototype.date = function() {
  var gigasecondBirthday = new Date( this.birthdate.setSeconds( this.birthdate.getSeconds() + Math.pow(10, 9) ) );
  var gigasecondBirthdayMidnight = gigasecondBirthday.setHours( 0, 0, 0, 0 );
  var getDate = new Date(gigasecondBirthdayMidnight);
  return getDate;
};